Conditional Skip

[wcampbell0x2a]

Great idea of a library.

I have a protocol that needs conditional parsing of fields in a struct. I see the skip attribute, but would something like a conditional skip be possible?

use deku::prelude::*;
use std::convert::TryFrom;

#[derive(PartialEq, Debug, DekuRead, DekuWrite)]
pub struct DekuTest {
    pub field_a: u8,
    #[deku(skip, if=(field_a, 1))]
    pub field_b: Option<u8>,
    #[deku(skip, if=(field_b, Some(1)))]
    pub field_c: Option<u8>,
}

fn main() {
    let data: Vec<u8> = vec![0x01, 0x02];

    let value = DekuTest::from_bytes((data.as_ref(), 0)).unwrap();
    println!("{:#?}", value)
}

[sharksforarms]

I like the idea! Shouldn't be too hard to implement. I can get to it next week most likely, also reminds me of a cond attribute for a conditional parsing, which may cover your use case

[sharksforarms]

If you don't mind taking a look to see if it meets your use-case, I plan on making a release tomorrow morning.

In the case of your original ticket:

use deku::prelude::*;
use std::convert::TryFrom;

#[derive(PartialEq, Debug, DekuRead, DekuWrite)]
pub struct DekuTest {
    pub field_a: u8,
    #[deku(skip, cond="*field_a == 1")] // skip if field_a == 1
    pub field_b: Option<u8>,
    #[deku(skip, cond="*field_b == Some(1)")] // skip if field_b == Some(1)
    pub field_c: Option<u8>,
}

fn main() {
    let data: Vec<u8> = vec![0x01, 0x02];

    let value = DekuTest::from_bytes((data.as_ref(), 0)).unwrap();
    println!("{:#?}", value)
}

DekuTest {
        field_a: 1,
        field_b: None,
        field_c: Some(
            2,
        ),
    },

[wcampbell0x2a]

I shall

[wcampbell0x2a]

Perfect, works as expected